Core/Scripts: Split script subdirectories into independent modules

* Makes it possible to define the linkage for every module
* Move the ScriptPCH into the root directory
* Changes the SCRIPTS cmake variable to a string type:
  -> -DSCRIPTS=0 is -DSCRIPTS="minimal-static" now
     (builds commands and spells statically)
  -> -DSCRIPTS=1 is -DSCRIPTS="static" now
     (builds all modules statically)
  -> -DSCRIPTS="dynamic"
     (builds all modules dynamically)
  -> Also the default value which is provided by the SCRIPTS
     variable is overwriteable through the SCRIPTS_COMMANDS,
     SCRIPTS_SPELLS... variable.

cmake/compiler/gcc/settings.cmake

@@ -35,7 +35,7 @@ if( WITH_COREDEBUG )
   message(STATUS "GCC: Debug-flags set (-g3)")
 endif()
 
-if (WITH_DYNAMIC_LINKING)
+if (BUILD_SHARED_LIBS)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -fvisibility=hidden -Wno-attributes")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fvisibility=hidden -Wno-attributes")
 
@@ -45,4 +45,4 @@ if (WITH_DYNAMIC_LINKING)
   # set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,--no-undefined")
 
   message(STATUS "GCC: Enabled shared linking")
-endif()
+endif()